Type I diabetes mellitus (also known as insulin-dependent diabetes, juvenile onset diabetes) is a form of diabetes mellitus that results from autoimmune destruction of insulin-producing beta-cells of the pancreas. The subsequent lack of insulin leads to increased blood and urine glucose. The classical symptoms are polyuria (frequent urination), polydipsia (increased thirst), polyphagia (increased hunger) and weight loss.
There is currently no effective cure for type I diabetes that restores the normal function of the pancreas, and treatment of type I diabetes is mainly focused on maintaining normal levels of blood sugar or glucose. Type I diabetes is usually treated with insulin replacement therapy, for example via subcutaneous injection, along with attention to dietary management and careful monitoring of blood glucose levels using glucose meters. Other treatment options include islet cell transplantation or whole pancreas transplantation, which may restore proper glucose regulation. However, as with any organ transplantation, the transplant recipient is required to take immunosuppressive drugs that are associated with a number of adverse effects, and therefore these options are not widely used. Complications of type I diabetes may be associated with both low blood sugar and high blood sugar. Low blood sugar may lead to seizures or episodes of unconsciousness and requires emergency treatment. High blood sugar may lead to increased fatigue and can also result in long term damage to organs.
Although the exact mechanism of type I diabetes development is not completely known, it is believed that auto-reactive CD4+ and CD8+ T lymphocytes are the main mediators of the beta-cells destruction. Other immune cells are also thought to play a role in the development and progression of the disease, for example, T regulatory (Treg) cells and T helper (Th) cells. There is also evidence implicating involvement of dendritic cells, macrophages and B lymphocytes.
The autoimmune attack directed against the beta-cells is believed to occur several years (5 years or more) before the clinical presentation of diabetes. However, even after the diagnosis of diabetes there is still significant beta-cell function, whose further decline may be prevented or arrested by immunological interventions.
Proposed immunotherapeutic interventions in type I diabetes include both antigen specific and non-antigenic specific therapy (reviewed in Masharani et al. (2010) Expert Opin Biol Ther, 10(3):459-65; and Bluestone et al. (2010) Nature, 464(7293):1293-300).
Antigen specific therapies are aimed at controlling the autoimmune process by inducing antigen specific tolerance. The rationale is to generate antigen specific regulatory T cells that induce anergy/deletion of auto-reactive effector T cells. One of the challenges in type I diabetes is identifying the pathogenic epitopes at the initiation of the disease. After the onset of the autoimmune injury, epitope spreading makes it difficult to identify specific target antigens. The antigens that have been suggested as potential tolerogens for type I diabetes include insulin and glutamic acid decarboxylase (GAD). Thus far, this approach has not been successful.
Non-antigenic specific therapy is not directed at a specific population of pathogenic T cells. For example, broad spectrum immunosuppressive agents, such as cyclosporine, azathioprine, prednisone and anti-thymocyte globulin that deplete or inactivate pathogenic T cells, have been tested for their effect on newly diagnosed type I diabetes. Although these drugs could decrease insulin requirements, the effect was modest and, as noted above, such drugs are associated with a number of adverse effects and are therefore not recommended for long term use.
The use of anti-CD3 antibodies has also been proposed as a non-antigen specific therapy that may arrest the loss of beta-cell function in new onset type I diabetes. These antibodies are specific to the c chain of the CD3 complex, which is the major signal transduction element of the T cell receptor. Clinical studies with, for example, teplizumab and otelixizumab, which are humanized anti-CD3 monoclonal antibodies, have provided evidence of preservation of insulin production in newly diagnosed type I diabetes patients, as evidenced by sustained C-peptide levels, a known indicator of endogenous insulin production. However, the duration of the effect and long-term efficacy is still unknown, and the use of anti-CD3 antibodies may induce undesirable side effects such as the activation of latent virus infections (Keymeulen B et al., (2010) Blood, 115(6):1145-55).
An anti-CD20 antibody, rituximab, inhibits B cells and has been shown to provoke C-peptide responses three months after diagnosis of type 1 diabetes. But, similar to the anti-CD3 antibodies, long-term effects of this antibody are still to be evaluated.
There is therefore a medical need for more effective means of type I diabetes treatment.
Beta-lactam compounds are a group of compounds containing a beta-lactam ring, namely a cyclic amide composed of three carbon atoms and one nitrogen atom. The beta-lactam ring is part of the structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems and monobactams, which are therefore referred to as beta-lactam antibiotics. These antibiotics work by inhibiting bacterial cell wall synthesis, thereby leading to a weakened cell wall and osmotic lysis of the bacterial cell. Bacteria can, however, become resistant to beta-lactam antibiotics, for example, by producing enzymes which hydrolyze the beta-lactam moiety and render the antibiotic inactive. These enzymes are generally referred to as beta-lactamases.
It was initially thought that beta-lactam antibiotics would not be able to directly affect mammalian cells, since mammalian cells do not produce cell walls. However, theoretically, beta-lactam compounds might bind eukaryotic cellular proteins and affect their functions. Indeed, screening of various compounds in models of amyotrophic lateral sclerosis led to the discovery that beta-lactam antibiotics could increase the expression of neuronal glutamate transporter in cultured mammalian cells. Moreover, ceftriaxone (cephalosporin family) was found to protect animals from several forms of glutamate-induced toxicity (Rothstein et al. (2005) Nature 433, 73-77).
Previous reports have addressed the possibility of penicillin binding to plasma proteins, which was suspected as the initial step in the sequence of events leading to adverse hypersensitivity reactions associated with this antibiotic. For example, Christie et al. (1987) Biochem Pharmacol, 36, 3379-3385 have synthesized a conjugate of albumin and benzylpenicillin (also known as penicillin G), and investigated its disposition and metabolism. Bertucci et al. (2001) Biochim Biophys Acta, 1544, 386-392 have studied structural and binding properties of albumin modified with penicillin G.
Various uses of antibiotics including for applications other than treatment of bacterial infections have been proposed.
WO 2007/099396 discloses a therapeutic kit to provide a safe and effective dosage of an antibiotic agent, and a foamable composition including an antibiotic agent, at least one organic carrier, a surface-active agent, at least one polymeric additive and water. WO 2007/099396 further discloses a method of treating, alleviating or preventing disorders of the skin, body cavity or mucosal surface, wherein the disorder involves inflammation as one of its etiological factors, including administering topically to a subject having the disorder, a foamed composition including: an antibiotic agent, inter alia beta-lactam antibiotics, at least one organic carrier, a surface-active agent, a polymeric additive and water.
U.S. Pat. No. 6,627,625 discloses therapeutic methods using beta-lactam compounds including beta-lactam antibiotics and beta-lactamase inhibitors.
Antibiotics not containing beta-lactam moieties have been previously reported to affect apoptosis and cytokine secretion by T cells. Moxifloxacin, a fluoroquinolone antibiotic, was reported to inhibit TNFα and IL-6 secretion by T cells (Choi et al. (2003) Antimicrob Agents Chemother, 47, 3704-3707). Rifampicin, an antibiotic drug of the rifamycin group, was found to inhibit CD95-induced apoptosis by T cells (Gollapudi et al. (2003) J Clin Immunol, 23, 11-22), and macrolide antibiotics were reported to induce apoptosis in T cells (Ishimatsu et al. (2004) Int J Antimicrob Agents, 24, 247-253; and Kadota et al. (2005) Int J Antimicrob Agents, 25, 216-220). Minocycline was found to inhibit TNFα and INFγ (Kloppenburg et al. (1996) Antimicrob Agents Chemother, 40, 934-940), and doxycycline demonstrated anti-inflammatory effects (Krakauer et al. (2003) Antimicrob Agents Chemother, 47, 3630-3633).
Previous work on the effects of antibiotics on experimental autoimmune diseases has shown that minocycline, fucidin and tetracycline could inhibit experimental autoimmune encephalomyelitis (EAE) (Giuliani et al. (2005) J Neuroimmunol, 165, 83-91; Brundula et al. (2002) Brain, 125, 1297-1308; Di Marco et al. (2001) Mult Scler, 7, 101-104; and Popovic et al. (2002) Ann Neurol, 51, 215-223). Oral vancomycin, which is poorly absorbed, was found to inhibit adjuvant arthritis by its effects on the intestinal flora (Nieuwenhuis et al. (2000) Arthritis Rheum, 43, 2583-2589). Tetracycline is used clinically as an immune modulator in patients with Pemphigus and Bullous Pemphigoid (Calebotta et al. (1999) Int J Dermatol, 38, 217-221; and Kolbach et al. (1995) Br J Dermatol, 133, 88-90).
WO 2003/061605 discloses methods for treating a host suffering from a chronic immune disease, e.g., multiple sclerosis or chronic fatigue syndrome. In practicing the subject methods, an effective amount of an elastase inhibitory agent, e.g., a beta-lactam containing compound, is administered to the host. Compositions for use in practicing the subject methods are also disclosed.
WO 2011/047153 discloses methods for inhibiting pathways induced by commensal bacteria of the gastrointestinal (GI) tract that lead to Th 17 differentiation, which in turn leads to localized and systemic accumulation of Th17 cells that are causally associated with inflammatory and autoimmune disorders, and methods for identifying agents useful for treating non-gut autoimmune disorders. WO 2011/047153 discloses, inter alia, a method for treating a subject having a non-gut autoimmune disorder, the method comprising administering to the subject a therapeutically effective amount of an inhibitor of a Th17 cell inducing bacterial species.
Nowhere is it disclosed or suggested that certain beta-lactam antibiotics can directly and effectively down-regulate pro-inflammatory phenotypes of T cells. Particularly, none of the prior art discloses or suggests that ampicillin can inhibit the development of type I diabetes, even when administered in a sub-antibacterial amount that does not produce an antibacterial effect. There is a medical need for compositions and methods useful for type I diabetes therapy.